The present invention relates to a sampler for liquid substances, especially a water sampler, comprising a body, a sampling container fitted with a sealable bottom and cover, as well as means for closing the sampling container of a sampler to be immersed in liquid upon a lowering cable at a desired depth by means of a weight dropped along said cable.
This type of samplers are particularly useful in limnological studies for picking up water samples from desired depths. The device is lowered down to s sampling depth in an open condition, it is closed by means of a weight dropped along a fastening cable and lifted up to the surface.
Various samplers have been used a long time for studying the condition and quality of waterways. Previously known is a so-called "Ruttner" sampler, comprising a cylindrical container whose bottom and cover, while maintaining their orientation, can be brought into an opened position from which a mechanism extending through the container retracts the sampler into a closed position whenever desired. Prior known are also models in which the covers at a lowering stage are set to be parallel to the vertical walls of a container portion, whereby the covers do not interfere with the changing of water in the container cylinder. In these models, at least the bottom cover is closed by means of a spring or lever system released with a throw weight. Prior known are also devices in which a cylinder is closed at a sampling depth by means of rubber plugs pulled into position by a rubber band stretched through the cylinder.
The following drawbacks can be mentioned in connection with the prior art samplers. Due to its poor flowthrough, the "Ruttner" type carries water from above down to the release depth. Since that model, the same as other models, has structural elements in its container cylinder, the equipment is hard to keep clean and objectionable matter may be released into a sample.
In models, wherein the flaps are hinged to open sideways, a drawback in intensive use and corrosion-inducing circumstances is that the spring systems of said covers are easily damaged and this, among other things, tends to cause leaks through the bottom cover. The samplers are generally heavy and daily work may take even several hours subjecting a worker to extra stress. In normal operation, the samplers must be held manually during drainage and e.g. the discharge cock is ordinarily at the bottom and thus difficult to handle. Aside from a few models used by marine researchers, the samplers cannot be fastened in series to one and the same cable in order to essentially reduce the working hours and often e.g. save expensive vessel-operating time.
The release mechanisms of the prior art models generally employ springs whose strength changes over extended use, which is why the device may release itself at a wrong depth or a throw weight shall not be sufficient to release it at all.
Structurally many samplers are complicated, include a plurality of minor components and modern rapid working techniques cannot be applied to their manufacture.
An object of the invention is to eliminate these drawbacks encountered in the above prior art samplers.